Surgical instrument comprising an electrode

ABSTRACT

A surgical instrument configured to deliver electrical energy to the tissue of a patient is disclosed. The surgical instrument comprises a frame, a first electrode, a second electrode, and a guard movable between a first position and a second position. The surgical instrument further comprises a spring positioned intermediate the guard and the frame. The spring is configured to bias the guard into the first position. When the guard is in the first position, a distal end of the guard is positioned at least flush with distal ends of the first electrode and the second electrode, which prevents current from arcing between the first electrode and the second electrode. When the guard is in the second position, the distal end of the guard is in contact with the tissue, which prevents current from arcing between the first electrode and the second electrode without passing through the tissue.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application claiming priority under 35 U.S.C. § 121 to U.S. patent application Ser. No. 12/641,837, entitled SURGICAL INSTRUMENT COMPRISING AN ELECTRODE, filed Dec. 18, 2009, now U.S. Pat. No. 9,028,483, the entire disclosure of which is hereby incorporated by reference herein.

BACKGROUND

i. Field of the Invention

The present invention generally relates to surgical devices and methods.

ii. Description of the Related Art

Traditional, or open, surgical techniques may require a surgeon to make large incisions in a patient's body in order to access a tissue treatment region, or surgical site. In some instances, these large incisions may prolong the recovery time of and/or increase the scarring to the patient. As a result, minimally invasive surgical techniques are becoming more preferred among surgeons and patients owing to the reduced size of the incisions required for various procedures. In some circumstances, minimally invasive surgical techniques may reduce the possibility that the patient will suffer undesirable post-surgical conditions, such as scarring and/or infections, for example. Further, such minimally invasive techniques can allow the patient to recover more rapidly as compared to traditional surgical procedures.

Endoscopy is one minimally invasive surgical technique which allows a surgeon to view and evaluate a surgical site by inserting at least one cannula, or trocar, into the patient's body through a natural opening in the body and/or through a relatively small incision. In use, an endoscope can be inserted into, or through, the trocar so that the surgeon can observe the surgical site. In various embodiments, the endoscope may include a flexible or rigid shaft, a camera and/or other suitable optical device, and a handle portion. In at least one embodiment, the optical device can be located on a first, or distal, end of the shaft and the handle portion can be located on a second, or proximal, end of the shaft. In various embodiments, the endoscope may also be configured to assist a surgeon in taking biopsies, retrieving foreign objects, and introducing surgical instruments into the surgical site.

Laparoscopic surgery is another minimally invasive surgical technique where procedures in the abdominal or pelvic cavities can be performed through small incisions in the patient's body. A key element of laparoscopic surgery is the use of a laparoscope which typically includes a telescopic lens system that can be connected to a video camera. In various embodiments, a laparoscope can further include a fiber optic system connected to a halogen or xenon light source, for example, in order to illuminate the surgical site. In various laparoscopic, and/or endoscopic, surgical procedures, a body cavity of a patient, such as the abdominal cavity, for example, can be insufflated with carbon dioxide gas, for example, in order to create a temporary working space for the surgeon. In such procedures, a cavity wall can be elevated above the organs within the cavity by the carbon dioxide gas. Carbon dioxide gas is usually used for insufflation because it can be easily absorbed and removed by the body.

In at least one minimally invasive surgical procedure, an endoscope and/or laparoscope can be inserted through a natural opening of a patient to allow a surgeon to access a surgical site. Such procedures are generally referred to as Nature Orifice Transluminal Endoscopic Surgery or (NOTES)™ and can be utilized to treat tissue while reducing the number of incisions, and external scars, to a patient's body. In various NOTES procedures, for example, an endoscope can include at least one working channel defined therein which can be used to allow the surgeon to insert a surgical instrument therethrough in order to access the surgical site.

The foregoing discussion is intended only to illustrate various aspects of the related art in the field of the invention at the time, and should not be taken as a disavowal of claim scope.

FIGURES

Various features of the embodiments described herein are set forth with particularity in the appended claims. The various embodiments, however, both as to organization and methods of operation, together with advantages thereof, may be understood in accordance with the following description taken in conjunction with the accompanying drawings as follows.

FIG. 1 illustrates one embodiment of an electrical ablation system.

FIGS. 2A-D illustrate one embodiment of the electrical ablation system in various phases of deployment.

FIG. 2E illustrates one embodiment of the electrical ablation device comprising multiple needle electrodes.

FIG. 3 illustrates one embodiment of the electrical ablation system shown in FIGS. 1 and 2A-D in use to treat undesirable tissue located on the surface of the liver.

FIG. 4 is a cross-sectional view of a surgical instrument comprising a first electrode, a second electrode, and a retractable sheath movable relative to the first electrode and the second electrode.

FIG. 5 is a perspective view of a distal end of the surgical instrument of FIG. 4 illustrating the sheath in an extended position.

FIG. 6 is a perspective view of a distal end of the surgical instrument of FIG. 4 illustrating the sheath in a retracted position.

FIG. 7 is a perspective view of a distal end of an alternative embodiment of a surgical instrument illustrating a first electrode, a second electrode, and insulative jackets positioned around the first electrode and the second electrode.

FIG. 8 is a cross-sectional view of the surgical instrument of FIG. 7 illustrating the first and second electrodes positioned within tissue and the insulative jackets positioned against the tissue.

FIG. 9 is a perspective view of a distal end of an alternative embodiment of a surgical instrument illustrating a first electrode, a second electrode, and an insulative guard, wherein the insulative guard is movable between an extended positioned in which it is positioned intermediate the distal ends of the first electrode and the second electrode and a retracted position in which it is displaced proximally relative to the distal ends of the first and second electrodes.

FIG. 10 is a cross-sectional view of the surgical instrument of FIG. 9 illustrating the distal ends of the first and second electrodes positioned against tissue and the insulative guard in its extended position.

FIG. 11 is a cross-sectional view of the surgical instrument of FIG. 9 illustrating the distal ends of the first and second electrodes inserted into the tissue and the insulative guard in a retracted position.

FIG. 12 is a perspective view of a distal end of an alternative embodiment of a surgical instrument comprising a flexible electrode.

FIG. 13 illustrates the surgical instrument of FIG. 12 positioned against the liver of a patient at one location and an additional surgical instrument comprising an electrode positioned against the liver at another location.

FIG. 14 illustrates the necrotic regions of liver tissue which can be created by the surgical instrument of FIG. 12 and the additional surgical instrument of FIG. 13.

FIG. 15 is another illustration of the necrotic regions of liver tissue which can be created by the surgical instrument of FIG. 12 and the additional surgical instrument of FIG. 13.

FIG. 16 illustrates an alternative embodiment of a surgical instrument comprising a flexible balloon positioned against the liver of a patient.

FIG. 17 is a perspective view of a distal end of a surgical instrument.

FIG. 18 is an end view of the surgical instrument of FIG. 17.

FIG. 19 is a graph of the voltage field that can be generated by the surgical instrument of FIG. 17.

FIG. 20 is an elevational view of a distal end of a surgical instrument.

FIG. 21 is an end view of the surgical instrument of FIG. 20.

Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate various embodiments of the invention, in one form, and such exemplifications are not to be construed as limiting the scope of the invention in any manner.

DESCRIPTION

Various embodiments are directed to apparatuses, systems, and methods for the electrical ablation treatment of undesirable tissue such as diseased tissue, cancer, malignant and benign tumors, masses, lesions, and other abnormal tissue growths. Numerous specific details are set forth to provide a thorough understanding of the overall structure, function, manufacture, and use of the embodiments as described in the specification and illustrated in the accompanying drawings. It will be understood by those skilled in the art, however, that the embodiments may be practiced without such specific details. In other instances, well-known operations, components, and elements have not been described in detail so as not to obscure the embodiments described in the specification. Those of ordinary skill in the art will understand that the embodiments described and illustrated herein are non-limiting examples, and thus it can be appreciated that the specific structural and functional details disclosed herein may be representative and do not necessarily limit the scope of the embodiments, the scope of which is defined solely by the appended claims.

Reference throughout the specification to “various embodiments,” “some embodiments,” “one embodiment,” or “an embodiment”, or the like, means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases “in various embodiments,” “in some embodiments,” “in one embodiment,” or “in an embodiment”, or the like, in places throughout the specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. Thus, the particular features, structures, or characteristics illustrated or described in connection with one embodiment may be combined, in whole or in part, with the features structures, or characteristics of one or more other embodiments without limitation.

It will be appreciated that the terms “proximal” and “distal” may be used throughout the specification with reference to a clinician manipulating one end of an instrument used to treat a patient. The term “proximal” refers to the portion of the instrument closest to the clinician and the term “distal” refers to the portion located furthest from the clinician. It will be further appreciated that for conciseness and clarity, spatial terms such as “vertical,” “horizontal,” “up,” and “down” may be used herein with respect to the illustrated embodiments. However, surgical instruments may be used in many orientations and positions, and these terms are not intended to be limiting and absolute.

Electrical ablation devices in accordance with the described embodiments may comprise one or more electrodes configured to be positioned into or proximal to undesirable tissue in a tissue treatment region (e.g., target site, worksite) where there is evidence of abnormal tissue growth, for example. In general, the electrodes comprise an electrically conductive portion (e.g., medical grade stainless steel) and are configured to electrically couple to an energy source. Once the electrodes are positioned into or proximal to the undesirable tissue, an energizing potential is applied to the electrodes to create an electric field to which the undesirable tissue is exposed. The energizing potential (and the resulting electric field) may be characterized by multiple parameters such as frequency, amplitude, pulse width (duration of a pulse or pulse length), and/or polarity. Depending on the diagnostic or therapeutic treatment to be rendered, a particular electrode may be configured either as an anode (+) or a cathode (−) or may comprise a plurality of electrodes with at least one configured as an anode and at least one other configured as a cathode. Regardless of the initial polar configuration, the polarity of the electrodes may be reversed by reversing the polarity of the output of the energy source.

In various embodiments, a suitable energy source may comprise an electrical waveform generator, which may be configured to create an electric field that is suitable to create irreversible electroporation in undesirable tissue at various electric filed amplitudes and durations. The energy source may be configured to deliver irreversible electroporation pulses in the form of direct-current (DC) and/or alternating-current (AC) voltage potentials (e.g., time-varying voltage potentials) to the electrodes. The irreversible electroporation pulses may be characterized by various parameters such as frequency, amplitude, pulse length, and/or polarity. The undesirable tissue may be ablated by exposure to the electric potential difference across the electrodes.

In one embodiment, the energy source may comprise a wireless transmitter to deliver energy to the electrodes using wireless energy transfer techniques via one or more remotely positioned antennas. Those skilled in the art will appreciate that wireless energy transfer or wireless power transmission is the process of transmitting electrical energy from an energy source to an electrical load without interconnecting wires. An electrical transformer is the simplest instance of wireless energy transfer. The primary and secondary circuits of a transformer are not directly connected and the transfer of energy takes place by electromagnetic coupling through a process known as mutual induction. Power also may be transferred wirelessly using RF energy. Wireless power transfer technology using RF energy is produced by Powercast, Inc. and can achieve an output of 6 volts for a little over one meter. Other low-power wireless power technology has been proposed such as described in U.S. Pat. No. 6,967,462, the entire disclosure of which is incorporated by reference herein.

The apparatuses, systems, and methods in accordance with certain described embodiments may be configured for minimally invasive ablation treatment of undesirable tissue through the use of irreversible electroporation to be able to ablate undesirable tissue in a controlled and focused manner without inducing thermally damaging effects to the surrounding healthy tissue. The apparatuses, systems, and methods in accordance with the described embodiments may be configured to ablate undesirable tissue through the use of electroporation or electropermeabilization. More specifically, in various embodiments, the apparatuses, systems, and methods in accordance with the described embodiments may be configured to ablate undesirable tissue through the use of irreversible electroporation. Electroporation increases the permeabilization of a cell membrane by exposing the cell to electric pulses. The external electric field (electric potential/per unit length) to which the cell membrane is exposed to significantly increases the electrical conductivity and permeability of the plasma in the cell membrane. The primary parameter affecting the transmembrane potential is the potential difference across the cell membrane. Irreversible electroporation is the application of an electric field of a specific magnitude and duration to a cell membrane such that the permeabilization of the cell membrane cannot be reversed, leading to cell death without inducing a significant amount of heat in the surrounding tissue. The destabilizing potential forms pores in the cell membrane when the potential across the cell membrane exceeds its critical membrane voltage causing the cell to die under a process known as apoptosis and/or necrosis. The application of irreversible electroporation pulses to cells is an effective way for ablating large volumes of undesirable tissue without deleterious thermal effects to the surrounding healthy tissue associated with thermal-inducing ablation treatments. This is because irreversible electroporation destroys cells without heat and thus does not destroy the cellular support structure or regional vasculature. A destabilizing irreversible electroporation pulse, suitable to cause cell death without inducing a significant amount of thermal damage to the surrounding healthy tissue, may have amplitude in the range of about several hundred to about several thousand volts and is generally applied across biological membranes over a distance of about several millimeters, for example, for a relatively long duration. Thus, the undesirable tissue may be ablated in-vivo through the delivery of destabilizing electric fields by quickly creating cell necrosis.

The apparatuses, systems, and methods for electrical ablation therapy in accordance with the described embodiments may be adapted for use in minimally invasive surgical procedures to access the tissue treatment region in various anatomic locations such as the brain, lungs, breast, liver, gall bladder, pancreas, prostate gland, and various internal body lumen defined by the esophagus, stomach, intestine, colon, arteries, veins, anus, vagina, cervix, fallopian tubes, and the peritoneal cavity, for example, without limitation. Minimally invasive electrical ablation devices may be introduced to the tissue treatment region using a trocar inserted though a small opening formed in the patient's body or through a natural body orifice such as the mouth, anus, or vagina using translumenal access techniques known as Natural Orifice Translumenal Endoscopic Surgery (NOTES)™. Once the electrical ablation devices (e.g., electrodes) are located into or proximal to the undesirable tissue in the treatment region, electric field potentials can be applied to the undesirable tissue by the energy source. The electrical ablation devices can comprise portions that may be inserted into the tissue treatment region percutaneously (e.g., where access to inner organs or other tissue is done via needle-puncture of the skin). Other portions of the electrical ablation devices may be introduced into the tissue treatment region endoscopically (e.g., laparoscopically and/or thoracoscopically) through trocars or working channels of the endoscope, through small incisions, or transcutaneously (e.g., where electric pulses are delivered to the tissue treatment region through the skin).

FIG. 1 illustrates one embodiment of an electrical ablation system 10. The electrical ablation system 10 may be employed to ablate undesirable tissue such as diseased tissues, cancers, tumors, masses, lesions, abnormal tissue growths inside a patient using electrical energy. The electrical ablation system 10 may be used in conjunction with endoscopic, laparoscopic, thoracoscopic, open surgical procedures via small incisions or keyholes, percutaneous techniques, transcutaneous techniques, and/or external non-invasive techniques, or any combinations thereof without limitation. The electrical ablation system 10 may be configured to be positioned within a natural body orifice of the patient such as the mouth, anus, or vagina and advanced through internal body lumen or cavities such as the esophagus, colon, cervix, urethra, for example, to reach the tissue treatment region. The electrical ablation system 10 also may be configured to be positioned and passed through a small incision or keyhole formed through the skin or abdominal wall of the patient to reach the tissue treatment region using a trocar. The tissue treatment region may be located in the brain, lungs, breast, liver, gall bladder, pancreas, prostate gland, various internal body lumen defined by the esophagus, stomach, intestine, colon, arteries, veins, anus, vagina, cervix, fallopian tubes, and the peritoneal cavity, for example, without limitation. The electrical ablation system 10 can be configured to treat a number of lesions and ostepathologies comprising metastatic lesions, tumors, fractures, infected sites, and/or inflamed sites. Once positioned into or proximate the tissue treatment region, the electrical ablation system 10 can be actuated (e.g., energized) to ablate the undesirable tissue. In one embodiment, the electrical ablation system 10 may be configured to treat diseased tissue in the gastrointestinal (GI) tract, esophagus, lung, or stomach that may be accessed orally. In another embodiment, the electrical ablation system 10 may be adapted to treat undesirable tissue in the liver or other organs that may be accessible using translumenal access techniques such as, without limitation, NOTES™ techniques, where the electrical ablation devices may be initially introduced through a natural orifice such as the mouth, anus, or vagina and then advanced to the tissue treatment site by puncturing the walls of internal body lumen such as the stomach, intestines, colon, cervix. In various embodiments, the electrical ablation system 10 may be adapted to treat undesirable tissue in the brain, liver, breast, gall bladder, pancreas, or prostate gland, using one or more electrodes positioned percutaneously, transcutaneously, translumenally, minimally invasively, and/or through open surgical techniques, or any combination thereof.

In one embodiment, the electrical ablation system 10 may be employed in conjunction with a flexible endoscope 12, as well as a rigid endoscope, laparoscope, or thoracoscope, such as the GIF-100 model available from Olympus Corporation. In one embodiment, the endoscope 12 may be introduced to the tissue treatment region trans-anally through the colon, trans-orally through the esophagus and stomach, trans-vaginally through the cervix, transcutaneously, or via an external incision or keyhole formed in the abdomen in conjunction with a trocar. The electrical ablation system 10 may be inserted and guided into or proximate the tissue treatment region using the endoscope 12.

In the embodiment illustrated in FIG. 1, the endoscope 12 comprises an endoscope handle 34 and an elongate relatively flexible shaft 32. The distal end of the flexible shaft 32 may comprise a light source and a viewing port. Optionally, the flexible shaft 32 may define one or more working channels for receiving various instruments, such as electrical ablation devices, for example, therethrough. Images within the field of view of the viewing port are received by an optical device, such as a camera comprising a charge coupled device (CCD) usually located within the endoscope 12, and are transmitted to a display monitor (not shown) outside the patient.

In one embodiment, the electrical ablation system 10 may comprise an electrical ablation device 20, a plurality of electrical conductors 18, a handpiece 16 comprising an activation switch 62, and an energy source 14, such as an electrical waveform generator, electrically coupled to the activation switch 62 and the electrical ablation device 20. The electrical ablation device 20 comprises a relatively flexible member or shaft 22 that may be introduced to the tissue treatment region using a variety of known techniques such as an open incision and a trocar, through one of more of the working channels of the endoscope 12, percutaneously, or transcutaneously, for example.

In one embodiment, one or more electrodes (e.g., needle electrodes, balloon electrodes), such as first and second electrodes 24 a,b, extend out from the distal end of the electrical ablation device 20. In one embodiment, the first electrode 24 a may be configured as the positive electrode and the second electrode 24 b may be configured as the negative electrode. The first electrode 24 a is electrically connected to a first electrical conductor 18 a, or similar electrically conductive lead or wire, which is coupled to the positive terminal of the energy source 14 through the activation switch 62. The second electrode 24 b is electrically connected to a second electrical conductor 18 b, or similar electrically conductive lead or wire, which is coupled to the negative terminal of the energy source 14 through the activation switch 62. The electrical conductors 18 a,b are electrically insulated from each other and surrounding structures, except for the electrical connections to the respective electrodes 24 a,b. In various embodiments, the electrical ablation device 20 may be configured to be introduced into or proximate the tissue treatment region using the endoscope 12 (laparoscope or thoracoscope), open surgical procedures, or external and non-invasive medical procedures. The electrodes 24 a,b may be referred to herein as endoscopic or laparoscopic electrodes, although variations thereof may be inserted transcutaneously or percutaneously. As previously discussed, either one or both electrodes 24 a,b may be adapted and configured to slideably move in and out of a cannula, lumen, or channel defined within the flexible shaft 22.

Once the electrodes 24 a,b are positioned at the desired location into or proximate the tissue treatment region, the electrodes 24 a,b may be connected to or disconnected from the energy source 14 by actuating or de-actuating the switch 62 on the handpiece 16. The switch 62 may be operated manually or may be mounted on a foot switch (not shown), for example. The electrodes 24 a,b deliver electric field pulses to the undesirable tissue. The electric field pulses may be characterized based on various parameters such as pulse shape, amplitude, frequency, and duration. The electric field pulses may be sufficient to induce irreversible electroporation in the undesirable tissue. The induced potential depends on a variety of conditions such as tissue type, cell size, and electrical pulse parameters. The primary electrical pulse parameter affecting the transmembrane potential for a specific tissue type is the amplitude of the electric field and pulse length that the tissue is exposed to.

In one embodiment, a protective sleeve or sheath 26 may be slideably disposed over the flexible shaft 22 and within a handle 28. In another embodiment, the sheath 26 may be slideably disposed within the flexible shaft 22 and the handle 28, without limitation. The sheath 26 is slideable and may be located over the electrodes 24 a,b to protect the trocar and prevent accidental piercing when the electrical ablation device 20 is advanced therethrough. Either one or both of the electrodes 24 a,b of the electrical ablation device 20 may be adapted and configured to slideably move in and out of a cannula, lumen, or channel formed within the flexible shaft 22. The second electrode 24 b may be fixed in place. The second electrode 24 b may provide a pivot about which the first electrode 24 a can be moved in an arc to other points in the tissue treatment region to treat larger portions of the diseased tissue that cannot be treated by fixing the electrodes 24 a,b in one location. In one embodiment, either one or both of the electrodes 24 a,b may be adapted and configured to slideably move in and out of a working channel formed within a flexible shaft 32 of the flexible endoscope 12 or may be located independently of the flexible endoscope 12. Various features of the first and second electrodes 24 a,b are described in more detail in FIGS. 2A-D.

In one embodiment, the first and second electrical conductors 18 a,b may be provided through the handle 28. In the illustrated embodiment, the first electrode 24 a can be slideably moved in and out of the distal end of the flexible shaft 22 using a slide member 30 to retract and/or advance the first electrode 24 a. In various embodiments either or both electrodes 24 a,b may be coupled to the slide member 30, or additional slide members, to advance and retract the electrodes 24 a,b, e.g., position the electrodes 24 a,b. In the illustrated embodiment, the first electrical conductor 18 a coupled to the first electrode 24 a is coupled to the slide member 30. In this manner, the first electrode 24 a, which is slideably movable within the cannula, lumen, or channel defined by the flexible shaft 22, can advanced and retracted with the slide member 30.

In various other embodiments, transducers or sensors may be located in the handle 28 of the electrical ablation device 20 to sense the force with which the electrodes 24 a,b penetrate the tissue in the tissue treatment zone. This feedback information may be useful to determine whether either one or both of the electrodes 24 a,b have been properly inserted in the tissue treatment region. As is particularly well known, cancerous tumor tissue tends to be denser than healthy tissue and thus greater force is required to insert the electrodes 24 a,b therein. The transducers or sensors 29 can provide feedback to the operator, surgeon, or clinician to physically sense when the electrodes 24 a,b are placed within the cancerous tumor. The feedback information provided by the transducers or sensors 29 may be processed and displayed by circuits located either internally or externally to the energy source 14. The sensor 29 readings may be employed to determine whether the electrodes 24 a,b have been properly located within the cancerous tumor thereby assuring that a suitable margin of error has been achieved in locating the electrodes 24 a,b.

In one embodiment, the input to the energy source 14 may be connected to a commercial power supply by way of a plug (not shown). The output of the energy source 14 is coupled to the electrodes 24 a,b, which may be energized using the activation switch 62 on the handpiece 16, or in one embodiment, an activation switch mounted on a foot activated pedal (not shown). The energy source 14 may be configured to produce electrical energy suitable for electrical ablation, as described in more detail below.

In one embodiment, the electrodes 24 a,b are adapted and configured to electrically couple to the energy source 14 (e.g., generator, waveform generator). Once electrical energy is coupled to the electrodes 24 a,b, an electric field is formed in the tissue from the voltage applied at the electrodes 24 a,b. The energy source 14 may be configured to generate electric pulses at a predetermined frequency, amplitude, pulse length, and/or polarity that are suitable to induce irreversible electroporation to ablate substantial volumes of undesirable tissue in the treatment region. For example, the energy source 14 may be configured to deliver DC electric pulses having a predetermined frequency, amplitude, pulse length, and/or polarity suitable to induce irreversible electroporation to ablate substantial volumes of undesirable tissue in the treatment region. The DC pulses may be positive or negative relative to a particular reference polarity. The polarity of the DC pulses may be reversed or inverted from positive-to-negative or negative-to-positive a predetermined number of times to induce irreversible electroporation to ablate substantial volumes of undesirable tissue in the treatment region.

In one embodiment, a timing circuit may be coupled to the output of the energy source 14 to generate electric pulses. The timing circuit may comprise one or more suitable switching elements to produce the electric pulses. For example, the energy source 14 may produce a series of n electric pulses (where n is any positive integer) of sufficient amplitude and duration to induce irreversible electroporation suitable for tissue ablation when the n electric pulses are applied to the electrodes 24 a,b. In one embodiment, the electric pulses may have a fixed or variable pulse length, amplitude, and/or frequency.

The electrical ablation device 20 may be operated either in bipolar or monopolar mode. In bipolar mode, the first electrode 24 a is electrically connected to a first polarity and the second electrode 24 b is electrically connected to the opposite polarity. For example, in monopolar mode, the first electrode 24 a is coupled to a prescribed voltage and the second electrode 24 b is set to ground. In the illustrated embodiment, the energy source 14 may be configured to operate in either the bipolar or monopolar modes with the electrical ablation system 10. In bipolar mode, the first electrode 24 a is electrically connected to a prescribed voltage of one polarity and the second electrode 24 b is electrically connected to a prescribed voltage of the opposite polarity. When more than two electrodes are used, the polarity of the electrodes may be alternated so that any two adjacent electrodes may have either the same or opposite polarities, for example.

In monopolar mode, it is not necessary that the patient be grounded with a grounding pad. Since a monopolar energy source 14 is typically constructed to operate upon sensing a ground pad connection to the patient, the negative electrode of the energy source 14 may be coupled to an impedance simulation circuit. In this manner, the impedance circuit simulates a connection to the ground pad and thus is able to activate the energy source 14. It will be appreciated that in monopolar mode, the impedance circuit can be electrically connected in series with either one of the electrodes 24 a,b that would otherwise be attached to a grounding pad.

In one embodiment, the energy source 14 may be configured to produce RF waveforms at predetermined frequencies, amplitudes, pulse widths or durations, and/or polarities suitable for electrical ablation of cells in the tissue treatment region. One example of a suitable RF energy source is a commercially available conventional, bipolar/monopolar electrosurgical RF generator such as Model Number ICC 350, available from Erbe, GmbH.

In one embodiment, the energy source 14 may be configured to produce destabilizing electrical potentials (e.g., fields) suitable to induce irreversible electroporation. The destabilizing electrical potentials may be in the form of bipolar/monopolar DC electric pulses suitable for inducing irreversible electroporation to ablate tissue undesirable tissue with the electrical ablation device 20. A commercially available energy source suitable for generating irreversible electroporation electric field pulses in bipolar or monopolar mode is a pulsed DC generator such as Model Number ECM 830, available from BTX Molecular Delivery Systems Boston, Mass. In bipolar mode, the first electrode 24 a may be electrically coupled to a first polarity and the second electrode 24 b may be electrically coupled to a second (e.g., opposite) polarity of the energy source 14. Bipolar/monopolar DC electric pulses may be produced at a variety of frequencies, amplitudes, pulse lengths, and/or polarities. Unlike RF ablation systems, however, which require high power and energy levels delivered into the tissue to heat and thermally destroy the tissue, irreversible electroporation requires very little energy input into the tissue to kill the undesirable tissue without the detrimental thermal effects because with irreversible electroporation the cells are destroyed by electric field potentials rather than heat.

In one embodiment, the energy source 14 may be coupled to the first and second electrodes 24 a,b by either a wired or a wireless connection. In a wired connection, the energy source 14 is coupled to the electrodes 24 a,b by way of the electrical conductors 18 a,b, as shown. In a wireless connection, the electrical conductors 18 a,b may be replaced with a first antenna (not shown) coupled the energy source 14 and a second antenna (not shown) coupled to the electrodes 24 a,b, wherein the second antenna is remotely located from the first antenna.

In one embodiment, the energy source may comprise a wireless transmitter to deliver energy to the electrodes using wireless energy transfer techniques via one or more remotely positioned antennas. As previously discussed, wireless energy transfer or wireless power transmission is the process of transmitting electrical energy from the energy source 14 to an electrical load, e.g., the abnormal cells in the tissue treatment region, without using the interconnecting electrical conductors 18 a,b. An electrical transformer is the simplest instance of wireless energy transfer. The primary and secondary circuits of a transformer are not directly connected. The transfer of energy takes place by electromagnetic coupling through a process known as mutual induction. Wireless power transfer technology using RF energy is produced by Powercast, Inc. The Powercast system can achieve a maximum output of 6 volts for a little over one meter. Other low-power wireless power technology has been proposed such as described in U.S. Pat. No. 6,967,462.

In one embodiment, the energy source 14 may be configured to produce DC electric pulses at frequencies in the range of about 1 Hz to about 10000 Hz, amplitudes in the range of about ±100 to about ±3000 VDC, and pulse lengths (e.g., pulse width, pulse duration) in the range of about 1 μs to about 100 ms. The polarity of the electric potentials coupled to the electrodes 24 a,b may be reversed during the electrical ablation therapy. For example, initially, the DC electric pulses may have a positive polarity and an amplitude in the range of about +100 to about +3000 VDC. Subsequently, the polarity of the DC electric pulses may be reversed such that the amplitude is in the range of about −100 to about −3000 VDC. In one embodiment, the undesirable cells in the tissue treatment region may be electrically ablated with DC pulses suitable to induce irreversible electroporation at frequencies of about 10 Hz to about 100 Hz, amplitudes in the range of about +700 to about +1500 VDC, and pulse lengths of about 10 μs to about 50 μs. In another embodiment, the abnormal cells in the tissue treatment region may be electrically ablated with an electrical waveform having an amplitude of about +500 VDC and pulse duration of about 20 ms delivered at a pulse period T or repetition rate, frequency f=1/T, of about 10 Hz. It has been determined that an electric field strength of 1,000V/cm is suitable for destroying living tissue by inducing irreversible electroporation.

FIGS. 2A-D illustrate one embodiment of the electrical ablation device 20 in various phases of deployment. In the embodiment illustrated in FIGS. 2A-D, the sheath 26 is disposed over the flexible shaft 22, however, those skilled in the art will appreciate that the sheath 26 may be disposed within the flexible shaft 22. The electrical ablation device 20 may be used in conjunction with the electrical ablation system 10 shown in FIG. 1. It will be appreciated that other devices and electrode configurations may be employed without limitation. FIG. 2A illustrates an initial phase of deployment wherein the sheath 26 is extended in the direction indicated by arrow 40 to cover the electrodes 24 a,b. The electrodes 24 a,b may have dimensions of about 0.5 mm, about 1 mm, or about 1.5 mm in diameter. It will be appreciated that the dimensions of the electrodes 24 a,b may be anywhere from about 0.5 mm to about 1.5 mm in diameter. The electrical ablation device 20 may be introduced into the tissue treatment region through a trocar, as illustrated in FIG. 3, for example. FIG. 2B illustrates another phase of deployment wherein the sheath 26 is retracted within the handle 28 in the direction indicated by arrow 42. In this phase of deployment, the first and second electrodes 24 a,b extend through the distal end of the flexible shaft 22 and are ready to be inserted into or proximate the tissue treatment region. The first electrode 24 a may be retracted in direction 42 through a lumen 44 formed in the flexible shaft 22 by holding the handle 28 and pulling on the slide member 30. FIG. 2C illustrates a transition phase wherein the first electrode 24 a is the process of being retracted in direction 42 by pulling on the slide member 30 handle, for example, in the same direction. FIG. 2D illustrates another phase of deployment wherein the first electrode 24 a is in a fully retracted position. In this phase of deployment the electrical ablation device 20 can be pivotally rotated about an axis 46 defined by the second electrode 24 b. The electrodes 24 a,b are spaced apart by a distance “r.” The distance “r” between the electrodes 24 a,b may be 5.0 mm, about 7.5 mm, or about 10 mm. It will be appreciated that the distance “r” between the electrodes 24 a,b may be anywhere from about 5.0 mm to about 10.0 mm. Thus, the electrical ablation device 20 may be rotated in an arc about the pivot formed by the second electrode 24 b, the first electrode 24 a may be placed in a new location in the tissue treatment region within the radius “r.” Retracting the first electrode 24 a and pivoting about the second electrode 24 b enables the surgeon or clinician to target and treat a larger tissue treatment region essentially comprising a circular region having a radius “r,” which is the distance between the electrodes 24 a,b. Thus, the electrodes 24 a,b may be located in a plurality of positions in and around the tissue treatment region in order to treat much larger regions of tissue. Increasing the electrode 24 a,b diameter and spacing the electrodes 24 a,b further apart enables the generation of an electric field over a much larger tissue regions and thus the ablation of larger volumes of undesirable tissue. In this manner, the operator can treat a larger tissue treatment region comprising cancerous lesions, polyps, or tumors, for example.

Although the electrical ablation electrodes according to the described embodiments have been described in terms of the particular needle type electrodes 24 a,b as shown and described in FIGS. 1 and 2A-D, those skilled in the art will appreciate that other configurations of electrical ablation electrodes may be employed for the ablation of undesirable tissue, without limitation. In one embodiment, the electrical ablation device 20 may comprise two or more fixed electrodes that are non-retractable. In another embodiment, the electrical ablation device 20 may comprise two or more retractable electrodes, one embodiment of which is described below with reference to FIG. 2E. In another embodiment, the electrical ablation device 20 may comprise at least one slideable electrode disposed within at least one working channel of the flexible shaft 32 of the endoscope 12. In another embodiment, the electrical ablation device 20 may comprise at least one electrode may be configured to be inserted into the tissue treatment region transcutaneously or percutaneously. Still in various other embodiments, the electrical ablation device 20 may comprise at least one electrode configured to be introduced to the tissue treatment region transcutaneously or percutaneously and at least one other electrode may be configured to be introduced to the tissue treatment region through at least one working channel of the flexible shaft 32 of the endoscope 12. The embodiments, however, are not limited in this context.

FIG. 2E illustrates one embodiment of an electrical ablation device 100 comprising multiple needle electrodes 124 m, where m is any positive integer. In the illustrated embodiment, the electrical ablation device 100 comprises four electrodes 124 a, 124 b, 124 c, 124 d. It will be appreciated that in one embodiment, the electrical ablation device 800 also may comprise three needle electrodes 124 a, 124 b, 124 c, without limitation. The electrical ablation device 100 may be used in conjunction with the electrical ablation system 10 shown in FIG. 1. It will be appreciated that other devices and electrode configurations may be employed without limitation. The electrodes 124 a-m each may have dimensions of about 0.5 mm, about 1 mm, or about 1.5 mm in diameter. It will be appreciated that the dimensions of each of the electrodes 124 a-m may be anywhere from about 0.5 mm to about 1.5 mm in diameter. The electrical ablation device 100 may be introduced into the tissue treatment region through a trocar, as subsequently described and illustrated with reference to FIG. 3, for example.

The electrical ablation device 100 comprises essentially the same components as the electrical ablation device 20 described with reference to FIGS. 2A-D. The electrical ablation device 100 comprises the relatively flexible member or shaft 22, the protective sheath 26, and one or more handles 28 to operate either the sheath 26, the electrodes 124 a,b,c,d, or both. The electrodes 124 a,b,c,d may be individually or simultaneously deployable and/or retractable in the direction indicated by arrow 142. The electrodes 124 a,b,c,d extend out from the distal end of the electrical ablation device 100. In one embodiment, the first and second electrodes 124 a, 124 b may be configured as the positive electrode coupled to the anode of the energy source 14 via corresponding first and second electrical conductors 118 a, 118 b, and the third and fourth electrodes 124 c, 124 d may be configured as the negative electrode coupled to the cathode of the energy source 14 via corresponding third and fourth electrical conductors 118 c, 118 d, or similar electrically conductive leads or wires, through the activation switch 62. Once the electrodes 124 a,b,c,d are positioned at the desired location into or proximate the tissue treatment region, the electrodes 124 a,b,c,d may be connected/disconnected from the energy source 14 by actuating/de-actuating the switch 62.

As previously discussed with reference to FIGS. 2A-D, as shown in FIG. 2E in one embodiment, the protective sleeve or sheath 26 may be slideably disposed over the flexible shaft 22 and within the handle 28. In an initial phase of deployment, the sheath 26 is extended in direction 40 to cover the electrodes 124 a,b,c,d to protect the trocar and prevent accidental piercing when the electrical ablation device 100 is advanced therethrough. Once the electrodes 124 a,b,c,d are located into or proximate the tissue treatment region, the sheath 26 is retracted in direction 42 to expose the electrodes 124 a,b,c,d. One or more of the electrodes 124 a,b,c,d of the electrical ablation device 100 may be adapted and configured to slideably move in and out of a cannula, lumen, or channel formed within the flexible shaft 22. In one embodiment all of the electrodes 124 a,b,c,d are configured to slideably move in and out channels formed within lumens formed within the flexible shaft 22, referred to for example as the lumen 44 in FIGS. 2A-D, to advance and retract the electrodes 124 a,b,c,d as may be desired by the operator. Nevertheless, in other embodiments, it may be desired to fix all or certain ones of the one or more electrodes 124 a,b,c,d in place.

The various embodiments of electrodes described in the present specification, e.g., the electrodes 24 a,b, or 124 a-m, may be configured for use with an electrical ablation device (not shown) comprising an elongated flexible shaft to house the needle electrodes 24 a,b, or 124 a-m, for example. The needle electrodes 24 a,b, or 124 a-m, are free to extend past a distal end of the electrical ablation device. The flexible shaft comprises multiple lumen formed therein to slideably receive the needle electrodes 24 a,b, or 124 a-m. A flexible sheath extends longitudinally from a handle portion to the distal end. The handle portion comprises multiple slide members received in respective slots defining respective walls. The slide members are coupled to the respective needle electrodes 24 a,b, or 124 a-m. The slide members are movable to advance and retract the electrode 24 a,b, or 124 a-m. The needle electrodes 24 a,b, or 124 a-m, may be independently movable by way of the respective slide members. The needle electrodes 24 a,b, or 124 a-m, may be deployed independently or simultaneously. An electrical ablation device (not shown) comprising an elongated flexible shaft to house multiple needle electrodes and a suitable handle is described with reference to FIGS. 4-10 in commonly owned U.S. patent application Ser. No. 11/897,676 titled “ELECTRICAL ABLATION SURGICAL INSTRUMENTS,” filed Aug. 31, 2007, now U.S. Patent Application Publication No. 2009/0062788, the entire disclosure of which is incorporated herein by reference in its entirety.

It will be appreciated that the electrical ablation devices 20, 100 described with referenced to FIGS. 2A-E, may be introduced inside a patient endoscopically, transcutaneously, percutaneously, through an open incision, through a trocar (as shown in FIG. 3), through a natural orifice, or any combination thereof. In one embodiment, the outside diameter of the electrical ablation devices 20, 100 may be sized to fit within a working channel of an endoscope and in other embodiments the outside diameter of the electrical ablation devices 20, 100 may be sized to fit within a hollow outer sleeve, or trocar, for example.

FIG. 3 illustrates one embodiment of the electrical ablation system 10 shown in FIGS. 1 and 2A-D in use to treat undesirable tissue 48 located on the surface of the liver 50. The undesirable tissue 48 may be representative of a variety of diseased tissues, cancers, tumors, masses, lesions, abnormal tissue growths, for example. In use, the electrical ablation device 20 may be introduced into or proximate the tissue treatment region through a port 52 of a trocar 54. The trocar 54 is introduced into the patient via a small incision 59 formed in the skin 56. The endoscope 12 may be introduced into the patient trans-anally through the colon, trans-orally down the esophagus and through the stomach using translumenal techniques, or through a small incision or keyhole formed through the patient's abdominal wall (e.g., the peritoneal wall). The endoscope 12 may be employed to guide and locate the distal end of the electrical ablation device 20 into or proximate the undesirable tissue 48. Prior to introducing the flexible shaft 22 through the trocar 54, the sheath 26 is slid over the flexible shaft 22 in a direction toward the distal end thereof to cover the electrodes 24 a,b (as shown in FIG. 2A) until the distal end of the electrical ablation device 20 reaches the undesirable tissue 48.

Once the electrical ablation device 20 has been suitably introduced into or proximate the undesirable tissue 48, the sheath 26 is retracted to expose the electrodes 24 a,b (as shown in FIG. 2B) to treat the undesirable tissue 48. To ablate the undesirable tissue 48, the operator initially may locate the first electrode 24 a at a first position 58 a and the second electrode 24 b at a second position 60 using endoscopic visualization and maintaining the undesirable tissue 48 within the field of view of the flexible endoscope 12. The first position 58 a may be near a perimeter edge of the undesirable tissue 48. Once the electrodes 24 a,b are located into or proximate the undesirable tissue 48, the electrodes 24 a,b are energized with irreversible electroporation pulses to create a first necrotic zone 65 a. For example, once the first and second electrodes 24 a,b are located in the desired positions 60 and 58 a, the undesirable tissue 48 may be exposed to an electric field generated by energizing the first and second electrodes 24 a,b with the energy source 14. The electric field may have a magnitude, frequency, and pulse length suitable to induce irreversible electroporation in the undesirable tissue 48 within the first necrotic zone 65 a. The size of the necrotic zone is substantially dependent on the size and separation of the electrodes 24 a,b, as previously discussed. The treatment time is defined as the time that the electrodes 24 a,b are activated or energized to generate the electric pulses suitable for inducing irreversible electroporation in the undesirable tissue 48.

This procedure may be repeated to destroy relatively larger portions of the undesirable tissue 48. The position 60 may be taken as a pivot point about which the first electrode 24 a may be rotated in an arc of radius “r,” the distance between the first and second electrodes 24 a,b. Prior to rotating about the second electrode 24 b, the first electrode 24 a is retracted by pulling on the slide member 30 (FIGS. 1 and 2A-D) in a direction toward the proximal end and rotating the electrical ablation device 20 about the pivot point formed at position 60 by the second electrode 24 b. Once the first electrode 24 a is rotated to a second position 58 b, it is advanced to engage the undesirable tissue 48 at point 58 b by pushing on the slide member 30 in a direction towards the distal end. A second necrotic zone 65 b is formed upon energizing the first and second electrodes 24 a,b. A third necrotic zone 65 c is formed by retracting the first electrode 24 a, pivoting about pivot point 60 and rotating the first electrode 24 a to a new location, advancing the first electrode 24 a into the undesirable tissue 48 and energizing the first and second electrodes 24 a,b. This process may be repeated as often as necessary to create any number of necrotic zones 65 p, where p is any positive integer, within multiple circular areas of radius “r,” for example, that is suitable to ablate the entire undesirable tissue 48 region. At anytime, the surgeon or clinician can reposition the first and second electrodes 24 a,b and begin the process anew. In other embodiments, the electrical ablation device 100 comprising multiple needle electrodes 124 a-m described with reference to FIG. 2E may be employed to treat the undesirable tissue 48. Those skilled in the art will appreciate that similar techniques may be employed to ablate any other undesirable tissues that may be accessible trans-anally through the colon, and/or orally through the esophagus and the stomach using translumenal access techniques. Therefore, the embodiments are not limited in this context.

In various embodiments, as outlined above, a surgical instrument can comprise a first electrode and a second electrode, wherein at least one the first and second electrodes can be operably coupled to a power source. In certain embodiments, as also outlined above, a first electrode can be operably coupled with a positive terminal of a voltage source and the second electrode can be operably coupled with a negative terminal of the voltage source, for example. In at least one embodiment, the first and second electrodes can comprise columnar, or point, electrodes which can be inserted into the tissue of a patient. In various circumstances, a voltage potential can be applied to the two electrodes such that a magnetic field can be created therebetween in order to treat the tissue positioned intermediate the electrodes. In some circumstances, the voltage potential may be sufficient to permit current to flow between the electrodes. Various devices are disclosed in commonly-owned co-pending U.S. patent application Ser. No. 12/352,375, entitled ELECTRICAL ABLATION DEVICES, which was filed on Jan. 12, 2009, the entire disclosure of which is incorporated by reference herein. While such devices may be suitable for their intended purposes, other devices disclosed herein can provide various advantages.

In various embodiments, referring now to FIGS. 4-6, a surgical instrument, such as surgical instrument 200, for example, can comprise a handle portion 228, a shaft portion 222, and one or more electrodes, such as electrodes 224 a and 224 b, for example. Referring to FIG. 4, handle portion 228 can comprise a first portion 231 and a second portion 233, wherein the first portion 231 and the second portion 233 can be moved relative to one another. Electrodes 224 a and 224 b can be mounted, or rigidly secured, to the first portion 231 wherein, in at least one embodiment, proximal ends of electrodes 224 a and 224 b can be mounted to first portion 231 such that the proximal ends of the electrodes do not move relative to first portion 231. In at least one embodiment, a sheath 226 of shaft portion 222 can be mounted, or rigidly secured, to second portion 233 such that, when second portion 233 is moved relative to first portion 231, sheath 226 can be moved relative to first electrode 224 a and/or second electrode 224 b. In various embodiments, second portion 233 can be moved between a first, or distal, position (FIG. 5) in which the distal end 223 of sheath 226 surrounds the distal ends 235 a, 235 b of electrodes 224 a, 224 b and a second, or proximal, position (FIG. 6) in which the distal end 223 of sheath 226 is retracted relative to the distal ends 235 a, 235 b of electrodes 224 a, 224 b.

In various embodiments, further to the above, sheath 226 can be moved between a distal position in which the distal ends 235 a, 235 b of electrodes 224 a, 224 b are positioned within the sheath 226 and a proximal position in which the distal ends 235 a, 235 b can extend distally from the distal end 223 of sheath 226. In at least one embodiment, the distal ends 235 a, 235 b of electrodes 224 a, 224 b can be recessed with respect to the distal end 223 of sheath 226 when sheath 226 is in its distal position. In use, the distal end 223 of sheath 226 can be positioned against tissue within a surgical site, for example, such that the electrodes 224 a, 224 b do not contact the tissue. Such embodiments may also allow the surgical instrument 200, or at least the distal end thereof, to be inserted through a trocar without the electrodes 224 a, 224 b coming into contact with, snagging on, and/or becoming damaged by the trocar. Once the distal end of the surgical instrument 200 has been suitably positioned relative to the targeted tissue, the sheath 226 can be retracted in order to expose the distal ends 235 a, 235 b of the electrodes 224 a, 224 b such that the electrodes can be inserted into the tissue. In various alternative embodiments, the distal ends 235 a, 235 b of electrodes 224 a, 224 b can be positioned in the same plane as the distal end of sheath 226 when the sheath 226 is in its distal-most position.

In various embodiments, as outlined above, the second portion 233 of handle 228 can be moved relative to the first portion 231 of handle 228 in order to move the sheath 226 relative to the electrodes 224 a, 224 b. In various circumstances, referring again to FIG. 4, the first portion 231 can be held in a stationary, or at least substantially stationary, position while the second portion 233 can be slid relative to first portion 231 by a surgeon, or other clinician, for example. In at least one embodiment, the first portion 231 can comprise a cylindrical, or at least substantially cylindrical, portion 235 and the second portion 233 can comprise a cylindrical, or at least substantially cylindrical, aperture 237 configured to receive the cylindrical portion 235 of first portion 231. The aperture 237 can be configured to closely receive cylindrical portion 235 such that relative movement therebetween can be limited to relative movement along a predetermined path, such as axis 239, for example. In certain embodiments, first portion 231 and second portion 233 can comprise one or more cooperating keys and/or grooves which can be configured to permit relative sliding movement therebetween along axis 239 while preventing, or at least inhibiting, relative movement therebetween which is transverse to axis 239.

In various embodiments, referring now to FIG. 7, a surgical instrument, such as surgical instrument 300, for example, can comprise a sheath 326 and one or more electrodes, such as electrodes 324 a and 324 b, for example. In use, similar to the above, the electrodes 324 a and 324 b can be inserted into tissue and a voltage differential can be applied to the electrodes such that current can flow from one electrode to the other and, in addition, flow through the tissue positioned intermediate and/or surrounding the electrodes 324 a and 324 b. In various embodiments, at least one electrode can comprise an insulative jacket surrounding at least a portion of the electrode such that current does not arc, or jump, between the electrodes of the surgical instrument without flowing through the tissue. In certain embodiments, such as those having two electrodes, for example, an insulative jacket may surround only one of the electrodes, wherein such an insulative jacket can be sufficient to prevent current from arcing between the electrodes. In at least one embodiment, an insulative jacket 341 a can surround at least a portion of electrode 324 a and, similarly, an insulative jacket 341 b can surround at least a portion of electrode 324 b. The insulative jackets can be comprised of any suitable material which can increase the dielectric resistance between the electrodes 324 a and 324 b, such as ceramic, for example. In various embodiments, as a result of the above, an insulative jacket at least partially surrounding an electrode can interrupt the air gap between the electrodes in order to reduce the possibility of current arcing between the electrodes.

In various embodiments, further to the above, insulative jacket 341 a can comprise a tube having an aperture, wherein electrode 324 a can extend through the aperture. In at least one embodiment, insulative jacket 341 a can be mounted, or rigidly secured, to a handle portion of surgical instrument 300 and can extend along a substantial length of electrode 324 a. The insulative jacket 341 a can be configured such that the distal end 335 a of electrode 324 a is not surrounded by insulative jacket 341 a and such that the distal end 335 a of electrode 324 a extends distally from the distal end 343 a of insulative jacket 341 a. Similar to the above, insulative jacket 341 b can comprise a tube having an aperture, wherein electrode 324 b can extend through the aperture. In at least one embodiment, insulative jacket 341 b can be mounted, or rigidly secured, to a handle portion of surgical instrument 300 and can extend along the length of electrode 324 b. The insulative jacket 341 b can be configured such that the distal end 335 b of electrode 324 b is not surrounded by insulative jacket 341 b and such that the distal end 335 b of electrode 324 b extends distally from the distal end 343 b of insulative jacket 341 b. In at least one such embodiment, the air gap between the electrodes 324 a and 324 b can be interrupted by the insulative jackets 341 a, 341 b except for the distance extending between the distal ends of the electrodes 324 a, 324 b and the distal ends of insulative jackets 341 a, 341 b.

Referring to FIG. 8, the distal ends 343 a, 343 b of electrodes 324 a, 324 b can be inserted into tissue such that, if the electrodes 324 a and 324 b are inserted a certain depth, insulative jacket 341 a and/or insulative jacket 341 b can contact the tissue. Once the insulative jacket 341 a and/or insulative jacket 341 b contacts the tissue, the insulative jackets can prevent, or at least inhibit, electrode 324 a and/or electrode 324 b from being further inserted into the tissue. In at least one embodiment, the distal end 343 a and/or distal end 343 b can comprise a datum which can define the maximum insertion depth of the electrode 324 a and/or electrode 324 b into the tissue. When the insulative jackets 341 a and 341 b are in contact with, or at least nearly in contact with, the tissue, very little, if any, uninterrupted air gap may exist between the electrodes 324 a and 324 b. In various circumstances, as a result, the possibility of current acting between the electrodes without passing through the tissue can be reduced. In various embodiments, the distal end 343 a of insulative jacket 341 a and the distal end 343 b of insulative jacket 341 b can lie along a common plane, or datum. In various other embodiments, although not illustrated, the distal ends 343 a and 343 b of insulative jackets 341 a and 341 b can define different datums and/or can provide for different insertion depths into the tissue, for example.

In various embodiments, referring now to FIG. 9, a surgical instrument, such as surgical instrument 400, for example, can comprise a sheath 426 and one or more electrodes, such as electrodes 424 a and 424 b, for example. In use, similar to the above, the electrodes 424 a and 424 b can be inserted into tissue and a voltage differential can be applied to the electrodes such that current can flow from one electrode to the other and, in addition, flow through the tissue positioned intermediate and/or surrounding the electrodes. The surgical instrument 400 can further comprise an insulative guard, such as guard 441, for example, which can be movable between a distal, or extended, position in which it is positioned intermediate the distal ends of the first electrode 424 a and the second electrode 424 b and a proximal, or retracted, position in which the guard 441 is displaced proximally relative to the distal ends of the first and second electrodes 424 a and 424 b. In various embodiments, the guard 441 can be biased into a distal position (FIG. 9) in which guard 441 is positioned intermediate the distal end 443 a of first electrode 424 a and the distal end 443 b of second electrode 424 b. In certain embodiments, the guard 441 can be biased into its distal position by a spring, such as compression spring 445, for example. More particularly, in at least one embodiment, spring 445 can be positioned intermediate a portion of sheath 426, such as support surface 447, for example, and a portion of insulative guard 441, such as surface 449 and/or projections extending therefrom, such that the compression spring 445 can apply a biasing force to guard 441 and hold guard 441 in its distal position. In such a distal position, the guard 441 can prevent, or at least reduce the possibility of, current from arcing between the electrodes.

As outlined above, the insulative guard 441 of surgical instrument 400 can be biased into its distal position by compression spring 445. In at least one embodiment, referring to FIG. 9, guard 441 can comprise a distal end 451 which can be positioned flush with the distal ends 443 a and 443 b of electrodes 424 a and 424 b. In at least one embodiment, the distal end 451 can be positioned along a datum defined by distal ends 443 a and 443 b. In certain other embodiments, although not illustrated, the distal end 451 of guard 441 can extend beyond the distal end 443 a and/or the distal end 443 b of the electrodes. As also outlined above, the guard 441 can be retracted proximally. In at least one embodiment, referring now to FIG. 10, the insulative guard 441 can be slid proximally within sheath 426 such that the insulative guard 441 is no longer positioned intermediate the distal ends 443 a and 443 b of the electrodes. In certain embodiments, referring now to FIG. 11, the surgical instrument 400 can be configured such that insulative guard 441 can be retracted as electrodes 424 a and 424 b are inserted into the tissue. More particularly, in at least one embodiment, the distal ends 443 a and 443 b of the electrodes and the distal end 451 of guard 441 can be positioned against tissue wherein, as the electrodes 424 a and 424 b enter into the tissue, the guard 441 may not enter into the tissue and, instead, may be displaced proximally, or relative to the distal ends 443 a and 443 b. Once the guard has been displaced proximally, in various embodiments, a voltage differential may be applied to the electrodes 424 a and 424 b and current may flow from one electrode to the other through the tissue.

When insulative guard 441 is displaced proximally, as outlined above, the guard 441 can compress spring 445. When spring 445 is compressed, the spring 445 can store energy therein and apply a biasing force to insulative guard 441 such that, as the electrodes 424 a and 424 b are extracted from the tissue, the spring 445 can displace the guard 441 distally toward the distal ends 443 a and 443 b of electrodes 424 a and 424 b. In at least one such embodiment, the distal end 451 of guard 441 can remain in contact with the tissue as the electrodes 424 a and 424 b are inserted into and extracted from the tissue. In various embodiments, as a result, the guard 441 can prevent, or at least reduce the possibility of, current arcing between the electrodes without passing through the tissue. Stated another way, the guard 441 can be sufficiently retracted when the electrodes 424 a, 424 b are inserted into tissue in order to permit current to flow between the portions of electrodes 424 a, 424 b within the tissue but, at the same time, sufficiently positioned against the tissue to prevent, or at least reduce the possibility of, current from flowing between the electrodes 424 a, 424 b at a location outside of the tissue. In various embodiments, as a result of the above, the insulative guard 441 and spring 445 arrangement can provide for a self-regulating, or self-retracting, system. In other embodiments, although not illustrated, the surgical instrument 400 can comprise an actuator configured to displace the insulative guard 441. In certain embodiments, other biasing means can be used in addition to or in lieu of a spring. In at least one embodiment, for example, a surgical instrument can comprise a motor mounted within a shaft of the surgical instrument, wherein the motor can apply a biasing force to an insulative guard in order to keep the guard biased against the tissue and yet the permit the guard to move relative to the electrodes.

In various embodiments, further to the above, surgical instrument 400 can further comprise means for controlling or defining the movement of insulative guard 441 as it is moved between its proximal and distal positions. In at least one embodiment, referring to FIGS. 9 and 10, the sheath 426 can comprise at least one elongate slot 453 and the guard 441 can comprise at least one projection 455 extending therefrom, wherein the projection 455 can be configured to slide within the slot 453. The slot 453 can be configured to limit the movement of projection 455 such that the guard 441 can move along a predetermined path relative to sheath 426, for example. In at least one embodiment, the slot 453 and projection 455 can be configured such that guard 441 is guided along an axial, or longitudinal, path between its proximal and distal positions. In at least one such embodiment, the slot 453 can comprise a linear, or at least substantially linear, profile and can be parallel to, substantially parallel to, collinear with, or substantially collinear with a longitudinal axis of sheath 426. Although not illustrated, other embodiments are envisioned in which slot 453 can comprise a curved configuration, a curvilinear configuration, and/or any other suitable configuration in order to provide or define a suitable path for guard 441. In various embodiments, although not illustrated, the sheath 426 can comprise at least one projection extending therefrom which can be configured to slide within at least groove in the insulative guard. In various embodiments, referring again to FIGS. 9 and 10, the insulative guard 441 can comprise one or more recesses or grooves, such as recesses 457 a and 457 b, for example, which can be configured to receive at least a portion of the electrodes 424 a and 424 b, respectively. More particularly, in at least one embodiment, the electrode 424 a can extend through recess 457 a in guard 441 and, in addition, the electrode 424 b can extend through the recess 457 b, wherein, in at least one embodiment, the electrodes 424 a, 424 b can be closely received in the recesses 457 a, 457 b such that guard 441 is guided therebetween.

In various embodiments, a surgical instrument can include an electrode comprising a flexible portion which can be configured to conform to the surface of an organ, such as a patient's liver, for example, and/or any other suitable tissue to be treated. In certain embodiments, referring now to FIG. 12, a surgical instrument, such as surgical instrument 500, for example, can comprise a shaft 526 and an electrode 524, wherein the electrode 524 can be comprised of a flexible, conductive mesh 525. In at least one embodiment, the surgical instrument 500 can further comprise an electrode support 561 which can be mounted to the shaft 526. The electrode support 561 can comprise a wire, or rod, having a first end and a second end mounted to the shaft 526 and an intermediate portion 565 extending between the first end and the second end. The first end and the second end of electrode support 561 can be mounted to shaft 526 in any suitable manner, such as by welding and/or fasteners, for example. In various embodiments, the intermediate portion 565 can define a perimeter configured to support the edge of the flexible mesh 525. The edge of the flexible mesh 525 can be mounted to the electrode support 561 by any suitable means such as an adhesive and/or fasteners, for example. In certain embodiments, the edge of the flexible mesh 525 can be wrapped around the electrode support 561 such that the edge of the flexible mesh 525 can be attached to itself. In any event, the electrode mesh 525 can be configured such that a central portion of the electrode mesh 525 can move relative to its edge. In at least one embodiment, the central portion of the electrode mesh 525 can be configured to deflect relative to the electrode support 561 in order to create a pocket, or pouch. The electrode mesh 525 can comprise a concave or convex configuration which can receive at least a portion of the targeted tissue therein. In various embodiments, the surgical instrument 500 can comprise a liver retractor wherein the flexible mesh 525 can deflect to receive at least a portion of a patient's liver. In at least one such embodiment, the electrode 524 may be sufficiently rigid to allow a surgeon to manipulate the patient's liver with the surgical instrument 500 and hold the electrode 524 in position.

In various embodiments, further to the above, the flexible mesh 525 can be comprised of a conductive material, such as copper and/or stainless steel, for example, wherein the flexible mesh can be operably connected with at least one conductor, such as conductor 518, for example, of the surgical instrument 500. In use, the flexible mesh 525 can be positioned relative to the tissue to be treated wherein, in at least one embodiment, a second electrode, such as electrode 524 b, for example, can also be positioned relative to the tissue. Referring now to FIG. 13, the flexible electrode of surgical instrument 500 can be positioned on one side of the tissue to be treated and the second electrode can be inserted into the tissue and/or a tumor within the tissue, for example. In at least one such embodiment, the conductor 518 of surgical instrument 500 and the second electrode 524 b can be operably coupled with a power source such that current can flow between the electrodes. In various embodiments, the second electrode 524 b can be operably connected with a cathode, or positive pole, of the power source while the conductor 518 can be operably connected to an anode, or negative pole, of the power source and/or a suitable ground. In various other embodiments, the second electrode 524 b can be operably connected to the anode of the power source and/or ground while the conductor 518 can be operably connected to the cathode of the power source. In any event, referring to FIGS. 14 and 15, the voltage potential applied to the electrode 524 and the second electrode 524 b, and/or the current passing between the electrodes 524, 524 b, can cause necrosis in the tissue which is in contact with and/or surrounding the electrodes 524, 524 b. Such necrotic tissue can comprise necrotic tissue portion 563 a and necrotic tissue portion 563 b wherein, referring to FIG. 14, the necrotic tissue portion 563 b can be associated with the second electrode 524 b and can comprise a volume of substantially ablated and/or necrotic tissue while the necrotic tissue portion 563 a can be associated with electrode 524 and can comprise a volume of only partially ablated and/or necrotic tissue, for example.

In various circumstances, further to the above, it may be desirable to control or limit the size of necrotic tissue region 563 a and/or the density of the necrotic tissue within region 563 a. In certain embodiments, the amount and/or density of the necrotic tissue created around the electrode 524 can depend on the intensity, or density, of the current flowing from and/or to the electrode 524. In various circumstances, the field density of the current can depend on the size of the electrode 524. More particularly, a larger electrode 524 can produce a lower current field density surrounding the electrode 524 and, as a result, generate a smaller amount of necrotic tissue, whereas a smaller electrode 524 can produce a larger current field density and, as a result, generate a larger amount of necrotic tissue. In various embodiments, referring again to FIG. 14, the necrotic tissue region 563 a can be largely positioned under and/or around the electrode support 561. In view of the above, the perimeter or diameter of electrode support 561 can be increased such that a smaller amount of, and/or less dense volume of, necrotic tissue is created around electrode 524, whereas the perimeter or diameter of electrode support 561 can be decreased such that a larger amount of, and/or more dense volume of, necrotic tissue is created around electrode 524. Correspondingly, a larger perimeter or diameter of electrode support 561 can generally accommodate a larger electrode mesh 525, wherein the larger electrode mesh 525 can, as a result, contact a larger surface area of tissue. Such a larger surface area can further reduce the amount and/or density of necrotic tissue produced by electrode 524. By comparison, the amount and/or density of necrotic tissue surrounding second electrode 524 b, which may comprise a needle electrode, for example, can be larger, and possibly substantially larger, than the amount and/or density of necrotic tissue surrounding electrode 524.

As outlined above, referring again to FIG. 12, the electrode mesh 525 can comprise a conductive material. In at least one embodiment, the electrode mesh 525 can be attached to shaft 526 by a mounting collar 541, wherein the mounting collar 541 can secure an end of mesh 525 in position. In at least one embodiment, the electrode mesh 525 can comprise a bag having an open end which can be slid over electrode support 561 and at least a portion of shaft 526 wherein the mounting collar 541 can be slid over at least a portion of mesh 525 to mount mesh 525 to shaft 526. In certain embodiments, the electrode mesh can comprise at least one substrate material perfused with at least one electrically-conductive material, such as saline, for example, wherein the perfused material and the substrate material can permit current to flow throughout the mesh 525 and/or between conductor 518 and electrode support 561, for example. In various embodiments, the substrate material and the perfused material can both be comprised of one or more electrically-conductive materials. In at least one embodiment, the mesh 525 can be comprised of a non-conductive, or at least substantially non-conductive, substrate material, wherein a conductive material perfused within the substrate material can conduct the current within the mesh 525. In at least one embodiment, the substrate material of mesh 525 can be porous such that the substrate material can absorb the conductive material. In various embodiments, the electrode mesh 525 can comprise at least one substrate material and, in addition, at least one conductive material coated onto the substrate material. In at least one embodiment, the substrate material can be comprised of at least one non-electrically conductive material while, in other embodiments, the substrate material can be comprised of one or more electrically conductive materials. In certain embodiments, the coated material can be comprised of a multi-filament medical polyester yarn available from ATEX Technologies, for example. As discussed above, mesh 525 can be flexible such that it can readily deflect or change shape when it contacts tissue, such as a patient's liver, for example. In certain embodiments, the mesh 525 can comprise a material having a plurality of apertures extending therethrough, wherein the apertures can be arranged in any suitable pattern. In at least one embodiment, mesh 525 can comprise a weaved material. In certain embodiments, the mesh 525 can be rigid, or at least substantially rigid, such that it does not substantially deflect when it contacts tissue.

In various embodiments, referring now to FIG. 16, a surgical instrument, such as surgical instrument 600, for example, can comprise a flexible electrode, such as balloon electrode 624, for example, wherein the electrode 624 can be configured to conform to the contour of the tissue being treated. In certain embodiments, the balloon electrode 624 can be delivered to a surgical site percutaneously and/or laprascopically, wherein the balloon electrode 624 can be positioned under and/or around the targeted tissue, such as a patient's liver, for example. In at least one embodiment, the balloon electrode 624 can be expanded in order to increase the surface area of the electrode in contact with the targeted tissue. Similar to the above, a larger surface area in contact with the tissue can reduce the amount of, and/or the density of, the necrotic tissue created. In various embodiments, also similar to the above, a second electrode can be inserted into the targeted tissue, wherein the second electrode can be operably coupled with the cathode, or positive terminal, of a power source and the balloon electrode 624 can comprise a return electrode which can be operably coupled with the anode, or negative terminal, of the power source and/or any suitable ground, for example. In other embodiments, the electrode 624 can be operably coupled with the cathode, or positive terminal, of the power source and the second electrode can be operably coupled with the anode, or negative terminal, of the power source and/or any other suitable ground. In various alternative embodiments, a surgical instrument can include an electrode comprising a flexible sheet which is positioned against or relative to the targeted tissue.

In various embodiments, referring now to FIGS. 17 and 18, a surgical instrument, such as surgical instrument 700, for example, can comprise a plurality of electrodes, such as electrodes 724 a, 724 b, 724 c, and 724 d, for example, which can be configured and arranged to treat tissue in a desired manner. Similar to the above, the electrodes 724 a-724 d can extend distally from shaft 722 and protective sleeve 726 such that the electrodes can be inserted into tissue. In certain embodiments, also similar to the above, the electrodes 724 a and 724 b can be operably coupled with a cathode, or positive terminal, of a power source, whereas the electrodes 724 c and 724 d can be operably coupled with an anode, or negative terminal, of a power source. Referring primarily to FIG. 18, the electrodes 724 a-724 d can be positioned and arranged with respect to a central axis, such as axis 799, for example, wherein, in certain embodiments, axis 799 can be defined by the center of shaft 722. In various embodiments, the electrodes 724 a-724 d can each comprise a columnar electrode having a central axis, wherein the central axes of the electrodes 724 a-724 d can be positioned relative to axis 799. For example, the central axis of electrode 724 a can be positioned a distance D1 away from axis 799, the central axis of electrode 724 b can be positioned a distance D2 away from axis 799, the central axis of electrode 724 c can be positioned a distance D3 away from axis 799, and the central axis of electrode 724 d can be positioned a distance D4 away from axis 799. In certain embodiments, distance D1 can be equal to, or at least substantially equal to, distance D2 while, in various embodiments, distance D3 can be equal to, or at least substantially equal to, distance D4. Referring again to FIG. 18, distances D1 and D2 can be larger than distances D3 and D4 such that electrodes 724 a and 724 b care positioned further away from axis 799 than electrodes 724 c and 724 d. In various embodiments, distances D1, D2, D3, and/or D4 can range between approximately 0.25 cm and approximately 1.0 cm, for example.

When electrodes 724 a-724 d are polarized by a power source, referring again to FIG. 18, a voltage field can be created which surrounds the electrodes. In various embodiments, the voltage field can comprise one or more isolines, wherein each isoline can represent portions of the voltage field which have the same magnitude. For example, the voltage field generated by electrodes 724 a-724 d can be represented by a plurality of isolines, such as isoline 798 a, for example, wherein isoline 798 a can represent a perimeter surrounding the electrodes having a constant voltage field magnitude. Similarly, the electrodes 724 a-724 d can produce an isoline 798 b which can represent a perimeter surrounding the electrodes having a constant voltage field magnitude which is different than the magnitude of isoline 798 a, for example. In various embodiments, the isoline 798 b can represent a voltage field magnitude which is greater than the magnitude represented by isoline 798 a. In various embodiments, referring now to FIG. 19, the magnitude of the voltage field produced by the electrodes may not be constant at all locations surrounding the electrodes; on the contrary, the magnitude of the voltage field may be different at various locations surrounding the electrodes. For example, the voltage field, or at least a portion of the voltage field produced by the surgical instrument 700 can be represented by graph 797 a in FIG. 19. More particularly, the graph 797 a can represent the magnitude of the voltage field measured in a plane which includes the center axis of electrode 724 c, center axis 799, and electrode 724 d. Graph 797 a, however, may not necessarily represent the magnitude of the voltage field in other planes. Upon examining the graph 797 a, it can be seen that, in at least one embodiment, the voltage field produced by the electrodes 724 a-724 d can comprise a symmetrical, or at least substantially symmetrical, profile centered about axis 799. Furthermore, it can be seen from graph 797 a that the magnitude of the voltage field has two valleys 795 c, 795 d centered about, or at least positioned adjacent to, the electrodes 724 c and 724 d, respectively. In various embodiments, the magnitude of the voltage field at valleys 795 c and/or 795 d may be zero or, alternatively, greater than zero.

In various embodiments, referring again to the graph 797 a in FIG. 19, the magnitude of the voltage field surrounding electrodes 724 a-724 d can be the same, or at least substantially the same, at distances of between about 6 cm to about 10 cm away from axis 799 in the lateral directions, for example. Stated another way, the change in magnitude, or gradient, of the voltage field produced by surgical instrument 700 between about 6 cm and about 10 cm away from the center of surgical instrument 700 may be very small. In at least one embodiment, for example, the gradient, or rate of change of the magnitude of the voltage field, between about 9 cm and about 10 cm may be about 0.04 VDC per millimeter, for example. In other various embodiments, the gradient may be about 0.01 VDC/mm, about 0.02 VDC/mm, about 0.03 VDC/mm, about 0.05 VDC/mm, about 0.06 VDC/mm, about 0.07 VDC/mm, about 0.08 VDC/mm, about 0.09 VDC/mm, about 0.10 VDC/mm, about 0.11 VDC/mm, about 0.12 VDC/mm, and/or about 0.13 VDC/mm, for example. In various circumstances, it may be desirable for surgical instrument 700 to produce a voltage field having a gradient below about 0.14V/mm, wherein a voltage field gradient at or larger than 0.14 V/mm may cause a contraction of muscle, and/or other tissue, surrounding the surgical site. Referring now to the graph 797 b in FIG. 19, the graph 797 b can represent the magnitude of the voltage field measured in a plane which includes the center axis of electrode 724 a, center axis 799, and electrode 724 b, although the graph 797 b may not necessarily represent the magnitude of the voltage field in other planes. In various circumstances, the planes used to establish graphs 797 a and 797 b may be orthogonal, or perpendicular, to one another. Upon examining the graph 797 b, it can be seen that, in at least one embodiment, the voltage field produced by the electrodes 724 a-724 d can comprise a symmetrical, or at least substantially symmetrical, profile centered about axis 799. Furthermore, it can be seen from graph 797 b that the magnitude of the voltage field has two peaks 795 a, 795 b centered about, or at least positioned adjacent to, the electrodes 724 a and 724 b, respectively. Similar to the above, it can be seen from graph 797 b that the gradient of the magnitude of the voltage field between about 9 cm and about 10 cm away from axis 799 may be about 0.04 VDC per millimeter, for example. In other various embodiments, the gradient may be about 0.01 VDC/mm, about 0.02 VDC/mm, about 0.03 VDC/mm, about 0.05 VDC/mm, about 0.06 VDC/mm, about 0.07 VDC/mm, about 0.08 VDC/mm, about 0.09 VDC/mm, about 0.10 VDC/mm, about 0.11 VDC/mm, about 0.12 VDC/mm, and/or about 0.13 VDC/mm, for example.

Viewing graphs 797 a and 797 b together, further to the above, the voltage field produced by surgical instrument 700 between about 6 cm and about 10 cm away from axis 799 in all directions could be represented by a single isoline, or isoplane, which surrounds the electrodes 724 a-724 d. When electrodes 724 a-724 d are positioned in tissue, such an isoplane can represent very little, if any, voltage gradient through the tissue which, as a result, can result in little, if any contraction of the tissue within the 6 cm to 10 cm region, for example. As outlined above, referring against to graphs 797 a and 797 b in FIG. 19, the magnitude of the voltage field produced by the surgical instrument 700 is a function of the voltage potential, or differential, supplied to the electrodes 724 a-724 d. A lower voltage potential, or differential, supplied to the electrodes can result in a voltage field having a lower average magnitude as compared to when a higher voltage potential, or differential, is supplied to the electrodes 724 a-724 d. In various embodiments, further to the above, the same voltage potential, or at least substantially the same voltage potential, supplied to electrode 724 a can be supplied to electrode 724 b. In certain embodiments, the same voltage potential, or at least substantially the same voltage potential, supplied to electrode 724 c can be supplied to electrode 724 d.

In various embodiments, referring now to FIGS. 20 and 21, a surgical instrument, such as surgical instrument 900, for example, can comprise a first array of electrodes, such as electrodes 924 a, 924 b, and 924 c, for example, which can be operably coupled with a first conductor. In addition, the surgical instrument 900 can further comprise a second array of electrodes, such as electrodes 924 d, 924 e, and 924 f, for example, which can be operably coupled with a second conductor. Further to the above, the first conductor can be operably coupled with a cathode, or positive terminal, of a power source, whereas the second conductor can be operably coupled with an anode, or negative terminal, of the power source, for example. In various embodiments, referring primarily to FIG. 21, the electrodes 924 a-924 f can be arranged along first and second lines. More particularly, in at least one embodiment, electrodes 924 a, 924 e, and 924 c can be positioned along a first line while electrodes 924 d, 924 b, and 924 f can be positioned along a second line. In certain embodiments, the first line can be parallel to, or at least substantially parallel to, the second line. With regard to the first line of electrodes, in various embodiments, positive electrode 924 a can be positioned on one side of negative electrode 924 e while positive electrode 924 c can be positioned on the opposite side of electrode 924 e. Similarly, with regard to the second line of electrodes, negative electrode 924 d can be positioned on one side of positive electrode 924 b while negative electrode 924 f can be positioned on the opposite side of electrode 924 b. In certain embodiments, electrodes 924 a, 924 b, and 924 c can have the same, or at least substantially the same, voltage potential while, in at least one embodiment, electrodes 924 d, 924 e, and 924 f can have the same, or at least substantially the same, voltage potential.

In various embodiments, further to the above, the first array of electrodes comprising electrodes 924 a, 924 b, and 924 c can be set to a first polarity while the second array of electrodes comprising electrodes 924 d, 924 e, and 924 f can be set to a second polarity. In certain embodiments, the polarity of the first array of electrodes can be adjusted simultaneously while the polarity of the second array of electrodes can be adjusted simultaneously, and independently, of the first array of electrodes. In various embodiments, the electrode 924 a can be operably coupled to a first conductor, the electrode 924 b can be operably coupled to a second conductor, the electrode 924 c can be operably coupled to a third conductor, the electrode 924 d can be operably coupled with a fourth conductor, the electrode 924 e can be operably coupled with a fifth conductor, and the electrode 924 f can be operably coupled with a sixth conductor. In at least one such embodiment, each of the conductors can be operably coupled with an output of a voltage source, wherein the voltage source can be configured to supply different voltage potentials to one, some, and/or all of the conductors and their corresponding electrodes. In the exemplary embodiment of surgical instrument 900, such a voltage source could supply six different voltage potentials, wherein, in at least one embodiment, each of the voltage potentials could be adjusted before, and/or during, the operation of the surgical instrument.

In certain embodiments, referring again to FIG. 21, the electrodes 924 a, 924 e, and 924 c can be attached to and/or bonded to one another with an insulator positioned intermediate the electrodes 924 a, 924 e, and 924 c. Similarly, electrodes 924 d, 924 b, and 924 f can be attached to and/or bonded to one another within an insulator positioned intermediate the electrodes 924 d, 924 b, and 924 f. In various embodiments, air gaps can be present between the electrodes 924 a-924 f. In any event, although surgical instrument 900 is described and illustrated as comprising six electrodes, other embodiments are envisioned which can comprise less than six electrodes or more than six electrodes, such as embodiments comprising eight electrodes arranged in two rows of four electrodes, or embodiments comprising ten electrodes arranged in two rows of five electrodes, for example. Furthermore, although surgical instrument 900 is described and illustrated as comprising two rows of electrodes, other embodiments are envisioned which can comprise more than two rows of electrodes, such as embodiments comprising nine electrodes arranged in three rows of three electrodes, for example.

The embodiments of the devices described herein may be introduced inside a patient using minimally invasive or open surgical techniques. In some instances it may be advantageous to introduce the devices inside the patient using a combination of minimally invasive and open surgical techniques. Minimally invasive techniques may provide more accurate and effective access to the treatment region for diagnostic and treatment procedures. To reach internal treatment regions within the patient, the devices described herein may be inserted through natural openings of the body such as the mouth, anus, and/or vagina, for example. Minimally invasive procedures performed by the introduction of various medical devices into the patient through a natural opening of the patient are known in the art as NOTES™ procedures. Some portions of the devices may be introduced to the tissue treatment region percutaneously or through small-keyhole-incisions.

Endoscopic minimally invasive surgical and diagnostic medical procedures are used to evaluate and treat internal organs by inserting a small tube into the body. The endoscope may have a rigid or a flexible tube. A flexible endoscope may be introduced either through a natural body opening (e.g., mouth, anus, and/or vagina) or via a trocar through a relatively small-keyhole-incision incisions (usually 0.5-1.5 cm). The endoscope can be used to observe surface conditions of internal organs, including abnormal or diseased tissue such as lesions and other surface conditions and capture images for visual inspection and photography. The endoscope may be adapted and configured with working channels for introducing medical instruments to the treatment region for taking biopsies, retrieving foreign objects, and/or performing surgical procedures.

Preferably, the various embodiments of the devices described herein will be processed before surgery. First, a new or used instrument is obtained and if necessary cleaned. The instrument can then be sterilized. In one sterilization technique, the instrument is placed in a closed and sealed container, such as a plastic or TYVEK® bag. The container and instrument are then placed in a field of radiation that can penetrate the container, such as gamma radiation, x-rays, or high-energy electrons. The radiation kills bacteria on the instrument and in the container. The sterilized instrument can then be stored in the sterile container. The sealed container keeps the instrument sterile until it is opened in the medical facility. Other sterilization techniques can be done by any number of ways known to those skilled in the art including beta or gamma radiation, ethylene oxide, and/or steam.

Although the various embodiments of the devices have been described herein in connection with certain disclosed embodiments, many modifications and variations to those embodiments may be implemented. For example, different types of end effectors may be employed. Also, where materials are disclosed for certain components, other materials may be used. The foregoing description and following claims are intended to cover all such modification and variations.

Any patent, publication, or other disclosure material, in whole or in part, that is said to be incorporated by reference herein is incorporated herein only to the extent that the incorporated materials does not conflict with existing definitions, statements, or other disclosure material set forth in this disclosure. As such, and to the extent necessary, the disclosure as explicitly set forth herein supersedes any conflicting material incorporated herein by reference. Any material, or portion thereof, that is said to be incorporated by reference herein, but which conflicts with existing definitions, statements, or other disclosure material set forth herein will only be incorporated to the extent that no conflict arises between that incorporated material and the existing disclosure material. 

What is claimed is:
 1. A surgical instrument configured to deliver electrical energy to the tissue of a patient, comprising: a frame; a first electrode, comprising: an elongate portion defined along a first axis; and a distal portion configured to contact the tissue; a second electrode, comprising: an elongate portion defined along a second axis; and a distal portion configured to contact the tissue; a guard movable between a first position and a second position, wherein said guard is comprised of an electrically insulative material; and a spring positioned intermediate said guard and said frame, wherein said guard is positioned intermediate said distal portion of said first electrode and said distal portion of said second electrode when said guard is in said first position, wherein said spring is configured to bias said guard into said first position, and wherein said guard is retracted proximally with respect to said first electrode and said second electrode and not positioned intermediate said distal portion of said first electrode and said distal portion of said second electrode when said guard is in said second position, wherein when said guard is in said first position, a distal end of said guard is positioned at least flush with distal ends of said first electrode and said second electrode, which prevents current from arcing between said first electrode and said second electrode when said guard is in said first position; and wherein when said guard is in said second position, said distal end of said guard is in contact with the tissue, which prevents current from arcing between said first electrode and said second electrode without passing through the tissue when said guard is in said second position.
 2. The surgical instrument of claim 1, wherein said guard is configured to move from said first position to said second position when said first electrode and said second electrode are inserted into the tissue.
 3. The surgical instrument of claim 1, wherein said guard is configured to move from said first position to said second position when said guard contacts the tissue.
 4. A surgical instrument configured to deliver electrical energy to the tissue of a patient, comprising: a housing; a first electrode, comprising: a first elongate portion defined along a first axis; and a first distal portion; a second electrode, comprising: a second elongate portion defined along a second axis; and a second distal portion; a guard comprising a distal end, wherein said guard is positioned intermediate said first electrode and said second electrode; and a resilient member positioned intermediate said guard and said housing, wherein said guard is movable between a distal position and a proximal position, wherein said resilient member is configured to bias said guard into said distal position, wherein when said guard is in said distal position, said distal end of said guard is positioned at least flush with distal ends of said first electrode and said second electrode, which prevents current from arcing between said first electrode and said second electrode when said guard is in said distal position, and wherein when said guard is in said proximal position, said distal end of said guard is in contact with the tissue, which prevents current from arcing between said first electrode and said second electrode without passing through the tissue when said guard is in said proximal position.
 5. The surgical instrument of claim 4, wherein said guard is comprised of an electrically insulative material.
 6. The surgical instrument of claim 4, wherein said guard is configured to move from said distal position to said proximal position when said first electrode and said second electrode are inserted into the tissue.
 7. The surgical instrument of claim 4, wherein said guard is configured to move from said distal position to said proximal position when said guard contacts the tissue.
 8. The surgical instrument of claim 4, wherein said distal end of said guard extends beyond said first distal portion and said second distal portion when said guard is in said distal position.
 9. A surgical instrument configured to deliver electrical energy to the tissue of a patient, comprising: a sheath; a first electrode, comprising: a first elongate portion defined along a first axis; and a first distal end portion configured to contact the tissue; a second electrode, comprising: a second elongate portion defined along a second axis; and a second distal end portion configured to contact the tissue; a guard comprising a distal end, wherein said guard is movable between a first position and a second position; and a biasing means positioned intermediate said guard and said sheath, wherein said guard is positioned intermediate said first electrode and said second electrode, wherein said biasing means is configured to bias said guard into said first position, and wherein said distal end of said guard extends between said first distal end portion and said second distal end portion when said guard is in said first position, wherein said guard is retracted proximally with respect to said first electrode and said second electrode when said guard is in said second position, wherein when said guard is in said first position, said distal end of said guard is positioned at least flush with distal ends of said first electrode and said second electrode, which prevents current from arcing between said first electrode and said second electrode when said guard is in said first position; and wherein when said guard is in said second position, said distal end of said guard is in contact with the tissue, which prevents current from arcing between said first electrode and said second electrode without passing through the tissue when said guard is in said second position.
 10. The surgical instrument of claim 9, wherein said guard is comprised of an electrically insulative material.
 11. The surgical instrument of claim 9, wherein said guard is configured to move from said first position to said second position when said first electrode and said second electrode are inserted into the tissue.
 12. The surgical instrument of claim 9, wherein said guard is configured to move from said first position to said second position when said guard contacts the tissue.
 13. The surgical instrument of claim 9, wherein said distal end of said guard extends beyond said first distal end portion and said second distal end portion when said guard is in said first position.
 14. The surgical instrument of claim 9, wherein said distal end of said guard is positioned flush with said first distal end portion and said second distal end portion. 